This undated combination of photos provided by the FBI, left, and the California Department of Motor Vehicles show Tashfeen Malik, left, and Syed Rizwan Farook. Photo Credit: AP

SAN BERNARDINO, Calif. - Islamic State praised the perpetrators of the Southern California mass shooting as “soldiers” of the group’s cause in a radio broadcast, but did not claim responsibility for directing the attack.

In an English-language broadcast posted online Saturday, the terrorist organization referred to married couple Syed Rizwan Farook and Tashfeen Malik as “two soldiers of the Khilāfah,” or caliphate, and said they died “in the path of Allah.” It stopped short of claiming a direct role in the rampage.

Farook, 28, and Malik, 29, killed 14 people and wounded 21 in a military-style attack with assault weapons during a holiday party of Farook’s co-workers Wednesday in San Bernardino. The attackers died hours later in a shootout with police.

The Islamic State broadcast asked Allah to accept both attackers as “shuhadā” or martyrs, and referred to the victims as “disbelievers.”

Comments from the group, also known as ISIS or ISIL, came as investigators worked to clarify what caused a young couple with a 6-month-old daughter to commit the deadliest mass shooting in the United States since the 2012 massacre in Newtown, Connecticut, that killed 26. FBI officials said Friday they are investigating the San Bernardino attack as an act of terrorism.

Details about Pakistan-born Malik emerged in interviews with relatives, who said she once wore Western clothes but grew more conservative over the past three years. Lawyers for Farook’s family said she covered herself with a burqa, chose not to drive and avoided being in the same room as male in-laws.

Farook had contact with at least five people with ties to terrorism in the United States and overseas, and Malik pledged allegiance to Islamic State leader Abu Bakr al-Baghdadi in a Facebook post shortly before the assault, sources said.

FBI Director James Comey said there were signs the shooters had been “radicalized” and drew inspiration from foreign terrorists, but no evidence has emerged tying them to a “cell or network.”

Federal agents served a search warrant on a home early Saturday morning in Riverside, California, as the FBI probed how the couple obtained the two assault rifles used in the attack, officials said.

Authorities said the weapons were legally purchased, but the .223-caliber Smith &amp;amp; Wesson M&amp;amp;P 15 rifles were illegally modified to be fully automatic with magazine clips of 30 bullets.

FBI officials had already interviewed the person who bought the rifles but returned to search his home Saturday. Two people were detained at the home as a safety measure, but no arrests were made, authorities said. ABC News identified the buyer as a former neighbor of Farook’s.

Obama on Saturday was briefed on the latest details of the federal investigation, with the White House saying he learned of “several pieces of information that point to the perpetrators being radicalized to violence.”

Comey and Attorney General Loretta Lynch were among the officials briefing Obama. They did not release the specific information, but according to a news release, they told the president “they had as of yet uncovered no indication the killers were part of an organized group or formed part of a broader terrorist cell.”

Obama, the White House said, “directed his team to take all measures necessary to continue to protect the American people, which remains his highest priority.”

In his weekly radio address, the president urged patience as investigators put together a “full picture” of the attackers’ motives.

“It is entirely possible that these two attackers were radicalized to commit this act of terror,” Obama said. “And if so, it would underscore a threat we’ve been focused on for years — the danger of people succumbing to violent extremist ideologies.”

San Bernardino on Saturday began creeping back to normal. Authorities began allowing people who had escaped the attack at the Inland Regional Center to retrieve their vehicles.

While city police kept a “heightened alert” status — meaning all available officers work alternating 12-hour shifts — the largely commercial neighborhood in the southern end of the city, with strip malls and chain restaurants, resembled any other weekend day.

Signs of the massacre lingered in the growing memorials at either end of the police barricades around the site. People frequently pulled over to leave candles or flowers.

Farook and Malik rented a town house in Redlands, a few miles from the attack scene. Farook, who was born in Chicago and raised in Southern California, had worked as a restaurant health inspector for San Bernardino County since 2012. Malik, who was born in Pakistan and raised in Saudi Arabia, came to the United States on a fiancee visa in 2014.

Investigators found more than 4,500 rounds of ammunition and 12 crude pipe bombs in the couple’s home, suggesting they may have been planning additional attacks.

Farook’s family saw no signs that the couple were extremists, said David Chesley and Mohammad Abuershaid, lawyers for Farook’s mother and three siblings. They described Malik as “just a housewife” who was quiet, like her husband.